Presently, data cartridge libraries are primarily used to archive data, i.e., store data that is not immediately needed by a host computer, and provide archived data to the host computer when the data is needed. To elaborate, the typical data cartridge library receives data from a host computer and causes the data to be stored or recorded on the recording medium located in one or more cartridges.
When the host computer requires some of the data that was previously stored in a data cartridge, a request for the data is sent from the host computer to the library. In response, the library identifies the data cartridge(s) in which the desired data is located, retrieves the data from the recording medium with the cartridge(s), and transmits the retrieved data to the host computer system.
Presently, most data cartridge libraries are comprised of: (a) a frame/chassis/cabinet that defines an interior space; (b) a magazine structure that is located within the interior space and that provides a plurality of data cartridge storage spaces, which are each capable of accommodating at least one data cartridge; (c) one or more drives that are each located within the interior space and capable of writing data onto a recording medium located in a data cartridge and/or reading data from the recording medium located in a data cartridge; (d) a data cartridge transport device that is located within the interior space and capable of moving an individual data cartridge between any one of the plurality of data cartridge storage spaces and any one of the drives within the library; and (e) an interface for receiving data from and transmitting data to a host computer.
Typically, such a data cartridge library is capable of both storing data provided by a host computer and retrieving data previously stored in the library for the host computer. The storage of data involves using the transport device to move a data cartridge from one of the data cartridge storage spaces to a drive, using the drive to write the data provided by the host computer on the recording medium located within the cartridge, and after the data has been written on the recording medium, using the transport device to move the data cartridge from the drive to a data cartridge storage space. The retrieval of data involves using the transport device to move a data cartridge from one of the data cartridge storage spaces to a drive, using the drive to read the data on the recording medium located within the cartridge and provide the read data to the host computer, and after the data has been read from the recording medium, using the transport device to move the data cartridge from the drive to a data cartridge storage space.
As previously noted, a data cartridge library is comprised of a data cartridge transport that is capable of being used to move a data cartridge between any one of the magazine data cartridge storage locations and any one of the drives in the library. Typically, the data cartridge transport device is comprised of a picker and an elevator that moves the picker within the interior space. The picker is capable of inserting/extracting a data cartridge into/from any one of the magazine storage spaces and any one of the drives. Typically, the picker is comprised of: (a) a grasping device that is used to engage a data cartridge and (b) a pusher plate that carries the grasping device and that is capable of movement towards and away from a location that is capable of accommodating a data cartridge. The elevator serves to position the picker adjacent to a location that is capable of accommodating a data cartridge so that the picker can perform an insertion or extraction operation.
In an extraction operation, the elevator is used to position the picker adjacent to a space at which a data cartridge is located (typically, either a storage space associated with the magazine or a drive). After the picker has been positioned, the pusher plate is used to move the grasping device towards the data cartridge. After the grasping device has been positioned, the grasping device is then actuated to grasp the cartridge. At this point, the pusher plate is then moved away from the location at which the data cartridge was located to extract the data cartridge from the space.
In an insertion operation, the elevator is used to position the picker (which is assumed to be grasping a data cartridge) adjacent to the space at which a data cartridge is to be located. After the picker has been positioned, the pusher plate is then used to move the grasping device and the grasped data cartridge towards the space in which the data cartridge is to be located. After the pusher plate and grasping device have positioned the data cartridge in the space, the grasping device releases the data cartridge, and the pusher plate is moved away from the space to retract the grasping device.
Many data cartridge libraries are also comprised of an entry/exit port that allows a user to insert and/or extract a data cartridge from the library without powering down the transport device. To elaborate, absent an entry/exit port, if a user wants to insert/extract a data cartridge into/from a library, the user typically powers down the transport device to avoid being injured by the transport device during the insertion or extraction of the data cartridge. The entry/exit port allows a user to insert/extract a data cartridge into/from the library without being exposed to the transport device. As a consequence, the entry/exit port allows a data cartridge to be inserted/extracted into/from the library without having to power down the transport device. Typically, an entry exit port is comprised of a slot structure that defines at least one slot that is capable of accommodating at least one data cartridge and a device that places the structure in one of two states. In the first state, the device positions the slot structure such that a slot is exposed to the exterior environment. When the structure is in this state, a user can either insert a data cartridge into the slot or remove a data cartridge from the slot, without being exposed to the transport device in either case. In the second state, the device positions the slot structure such that a slot is exposed to the interior of the library and accessible by the transport device, which can either insert a cartridge into the slot or remove a cartridge from the slot. When the structure is in the second state, the user is not exposed to the transport device.
One type of entry/exit port that has evolved is comprised of: (a) a frame or support to/from which a magazine that can accommodate multiple data cartridges can be attached/detached; and (b) a device for placing the frame in one of the states. In the first state, the device positions the frame such that the frame is exposed to the exterior environment. When the structure is in this state, a user can either attach a magazine to the frame or detach a magazine from the frame. Further, the user can either insert/remove one or more data cartridges into/from the magazine. In the second state, the device positions the frame such that any magazine that is attached to the frame is exposed to the transport device. In this state, the transport device can load data cartridges into the magazine or remove data cartridges from the magazine, as needed. When the frame is in either state, a user is substantially shielded from the transport device.
Many data cartridge libraries also have a hinged door that allows a user access to the interior of the library. Typically, such a door is provided so that the transport device can be accessed for maintenance and repair.